Several applications require keeping birds away from protected areas, which we define herein as geographical areas that either threaten birds and/or are threatened by birds. Consider for example, mining and oil operations with associated tailings ponds that may be harmful to birds. Operators and regulators desire economical devices and methods designed to help keep birds from landing on these protected areas, i.e. the tailings ponds.
Electrical power generation structures such as wind turbines pose hazards to birds because birds flying through wind farms, especially during low visibility, can come in contact with turbine blades, which rotate within a confined altitude band up to a couple of hundred meters above the ground. In this example, the wind farm can be treated as a protected area. To protect birds flying at low altitudes, operators and regulators desire economical devices and methods that will cause birds to alter their flight paths when approaching protected areas so as to avoid collision with wind turbines.
Birds are a significant hazard to aviation safety. Billions of dollars in damage to aircraft and significant loss of life have been recorded as the result of birds colliding with aircraft (referred to as bird-aircraft strikes, or simply bird strikes), particularly while aircraft are on approach or departure in the vicinity of airports. Birds do not survive bird strikes. Several protected areas can be defined around an airport where bird-aircraft strike hazards (BASH) are known to be significant. Airport operators and their regulators desire economical devices and methods designed to cause birds to safely alter their flight path when approaching these protected areas so as to avoid collisions with aircraft. The airport environment requires particular care since we do not want to deter birds from entering one protected area only to steer them into another area of potentially greater hazard.
Farmers know all too well the damage that birds can do to their crops. They have employed all sorts of bird deterrent devices such as cannons and effigies to harass birds in an attempt to keep them away. If one treats precious crop areas as protected areas, farmers desire economical devices and methods to keep birds away from these protected areas in order to increase the quantity and quality of their crop yields.
In the above applications, several types of bird deterrents and bird harassment methods have been employed, some of which are automated and run unattended, and some of which are used by trained personnel. Automated deterrents such as propane cannons, effigies, acoustic devices that broadcast aversive auditory emissions such as alarm, distress, and predator vocalizations, and lasers operated in low-light have been used with some success but suffer from habituation—i.e., the birds get used to them and the deterrents eventually lose their effectiveness in harassing and deterring birds. Modern deterrents usually activate randomly in an attempt to increase the time duration before birds become habituated to them. Human-operated deterrents such as hand-held pyrotechnics and hand-held lasers are more effective because they are selectively used only against birds approaching or found within protected areas. As a result, habituation occurs slowly or not at all. These human-operated deterrents, however, are impractical to use in a continuous fashion over large protected areas or at night.
While radar-activated deterrent systems have been reported in use in rare cases, their effectiveness has not been quantified and reported. The systems were deployed to protect a tailings pond with an attempt to reduce habituation by activating deterrents only when birds were detected by the radar. In these limited cases, 2D radars were employed that did not provide bird altitude selectivity over the protected area. Also, the protected area was small, concentrated over water, and monitored from a single radar location.